This invention relates to an apparatus and a method for friction-fusing overlapping portions of plastic strapping to form a joint therebetween by the utilization of very high frequency movement with low amplitude. Plastic strapping of the type that can be used are those formulated from thermoplastic resin materials such as longitudinally oriented linear polymer material such as polypropylene. The friction-fusion technique is currently being utilized in devices where the overlapping strap ends are held together under substantial pressure and then moved relative to each other to develop a bodily sliding frictional generation of heat at the interface region. In the existing devices, there is used a reciprocating method of movement in which the strap ends are moved in the longitudinal direction relative to each other.